This Balboa spa heater operates at 240 volts and uses Balboa's revolutionary M7 technology. It comes with unions that connect to the plumbing of the hot tub and uses an incoloy heating element. This spa heater is compatible with a Balboa control system that uses and of the following part numbers: 53352, 53352-(XX), 53408, 53408-(XX), 54240, 54348, 55014, 55014-(XX)